From: Joel VanderWerf <vjoel@...>
Date: 2004-11-12T08:23:04+09:00
Subject: Re: non-nil, etc.  (was Re: true? & false?)

Hal Fulton wrote:
>   class Array
>     def null?
>       ! empty?
>     end
>   end
> 
>   class String
>     def null?
>       ! empty?
>     end
>   end
> 
>   class Hash
>     def null?
>       ! empty?
>     end
>   end
> 
>   class Fixnum
>     def null?
>       self == 0
>     end
>   end
> 
>   class File
>     def null?  # now a little fun
>       size == 0
>     end
>   end
> 
>   # And now even more fun
> 
>   class Nil
>     def null?
>       true
>     end
>     def nnil?   # for symmetry
>       false
>     end
>   end
> 
>   # And the most fun of all, our beloved nnull?
> 
>   class Object
>     def null
>       false     # until overridden
>     end
>     def nnull?
>       ! null?   # inherited by everyone
>     end
>   end

Why not just define #empty? for Fixum, File, NilClass, and Object, and 
then define nonempty? instead of (argh, can't... make... self... type... 
this...) nnull? ?

The possibility of confusion between nil and null is too great (for me 
at least).